1. Technical Field
The present invention relates to an ink composition for use in color ink jet printing and more particularly to a yellow ink composition, a magenta ink composition, a solvent system suitable for a color ink composition and a color ink jet printing method using said ink compositions.
2. Background Art
In the "color ink jet printing method" wherein a color image is formed using an ink jet printing method, it is a common technique to use at least a yellow ink, a magenta ink and a cyan ink.
In the color ink jet printing method, ink compositions for respective colors, as such, should first have a good color production property. In particular, it is preferred for a color to be faithfully produced even on plain paper, especially on acid paper.
Furthermore, there is a color ink jet printing method wherein, in addition to three colors (yellow, magenta and cyan), four colors of red, green, blue and black are formed by overprinting the three color ink compositions, i.e., a yellow ink, a magenta ink and a cyan ink, to effect seven colors printing. (Black may be formed by over-printing yellow, magenta and cyan, or alternatively, a black ink may be used.)
In this type of the color ink jet printing method, besides the good color production property of the ink compositions per se, it is important for the color ink compositions to produce faithful color tone of red, green and blue when mixed by overprinting. In general, an ink composition which has a good color production property when used alone cannot be expected to have a good color production property when mixed by overprinting. Furthermore, in many cases, even though a good colors can be realized on coated pater, a poor colors are produced on paper which has a high acidity. For this reason, there is a demand for ink compositions and combinations thereof that can realize the good color production when mixed by overprinting without limiting by properties of recording paper.
Furthermore, the color ink composition for ink jet printing should have properties commonly required for ink jet printing, such as cause neither clogging of nozzles nor a change in composition and properties during storage. In particular, after a printing is suspended for a certain period, it is desirable that the printing start without any troubles such as the deviation of the ink droplets from the ink path and the missing of dots. It is preferable that the "suspending period" that is a period by the time when the deviation of the ink droplets or the missing of dots is observed should be long. An ink composition which has a long "suspending period" is hereinafter referred as an ink composition excellent in intermittent jetting stability.